Christians believe that when the earth was created it was perfect and without anger, fear, pain, disasters etc. After The Fall of Man (Adam committing sin by trying to emulate God) Adam was cast out of The Garden of Eden and God told him that he'd chosen the way of sin and worldliness so was destined from then to suffer the consequences of his choice. Due to God giving Adam free will, this choice was Adam's alone. Suffering as a result of this event involves disease, animals preying upon one another, fear, anger, pain, jealousy etc., natural disasters and ultimately, death.
Whether people take this literally is a personal choice. Many see it as a metaphor for Man being predisposed to choosing sin over virtue and suffering the consequences as a result of this. Adam therefore represents all humankind. Humans sin, whereas other lifeforms don't as they weren't created to have our consciousness and awareness of God.
If you're a Christian, the route is back to God via Jesus Christ. This life on earth is seen as a temporary stop and not the ultimate destination, which is Heaven and reconciliation with God. Christians understand that suffering is part of life and an unfortunate consequence of our choices. They don't fear suffering or death, only being separated from God causes a legitimate fear.
Christ Himself suffered torture and execution so He's with everyone through their suffering, whether Christian or not as God loves everyone and wants everyone to know Him.
God isn't some sinister controller of humans by playing a galactic SIMS game. Zapping some people, but being kind to others.
Obviously, many people don't believe in this, I'm just presenting the Christian view. Some types of Christian (Protestant) will interpret differently no doubt.